The Data, Measures and Synthesis Core will serve as the intellectual center for the program project, and will provide the main locus for conceptual and methodological integration of the five component projects. Specifically, the functions of the core will include: (1) facilitating communication and intellectual exchange among the project leaders regarding the conceptualization of health care markets, including market definitions and measures for characterizing market structure and the safety net; (2) providing a locus for sharing information and developing common approaches to estimation problems; (3) processing data bases and constructing empirical measures of health care market structure and the safety net that will be used by more than one component project; (4) creating a library of contextual, market-level data on health care markets, market structure, and the safety net; and (5) producing reports and manuscripts that summarize and synthesize the findings of the program project. The methods used to make certain that the goals of the core are achieved will include meetings of the project leaders; use of dedicated support staff, including a project manager, computer programmer, and research assistant, to perform the work of the core; and use of external consultants with expertise in health care markets, managed care, and vulnerable populations to advise the component project leaders and help synthesize the work of the program project.